The primary objective of this program project is to expand our knowledge of thc acquired immunodeficiency syndrome (AIDS) in Brazil. This proposal includes a Core and 3 Projects: The Core will provide administrative and logistical support for the personnel in Bahia, Sao Paulo and New York. Project I will determine the seroprevalence and incidence of HIV infection and AIDS in high and low risk populations in Bahia and Sao Paulo and identify and characterize HIV isolates from patients. Project II will study the natural history of HIV infection in the sexual partners and children of AIDS patients and HIV-seropositive persons identified in project I. Heterosexual and perinatal transmission, co-factors for the acquisition of infection and development of disease, and the outcome of HIV infection will be studied. The natural history of HIV 1 and HIV 2 infections will be compared and contrasted. Project III will characterize the opportunistic infections and neoplasms in Brazilian AIDS patients in Sao Paulo and in Bahia. The outcome of co-infection with HIV and Leishmania donovani chagasi will be prospectively studied. Overall, these studies will provide fundamental data regarding HIV infection and AIDS in Brazil which is essential to the development of control strategies.